Re manual pricing condition types (only for interfaces)

Hi Gurus , can any one solve this??

There are two manual pricing condition types:

ZPMN: Manual Price (condition type entered manually by users)

ZPSY: System Price (condition type used by system interface to apply manual price)

ZPMN condition type will be manually entered by users. ZPSY condition type will be used for manual price updates by interfaces (ex: Returns, Credits/Debits, Payment Request Interfaces from Model N, etc.) that create Return/Credit/Debit Sales Orders.

Requirement will ensure that a ZPSY condition type is only entered in sales orders that are created through interfaces. In other words, it will prevent users from entering ZPSY condition type manually. This will ensure that Manual Price override report only provides list of orders that have price overridden by users (ZPMN condition type).

Need to identify a variable that will make a distinction between order created manually by users and order created automatically by an interface.